System for starting and operating gaseous discharge devices



Dec. 12, 1939. J. G. soLA 2,133,228

SYSTEM FOR STARTING.AND OPERATING GASEOUS DISCHARGE DEVICES Filed March 10, 1939 I 20 discontinued Patented Dec. 12, 1939 I. UNITED STA ES PATENT OFFICE SYSTEM roa. STARTING m GASEOUS mscmmcc DEVICES Joseph G. Sola, Oak Pa Electric 00., Chicago,

Delaware Kpplication Mai-cam,

gaseous disvide an improved arrangement of this type by means of which the electrodes in an electric gaseous discharge device will be heated to a' temperature at which the free electron emission therefrom will support the normal discharge current and a voltage surge will then be applied to the tube between its electrodes for starting the tube in operation.

It is another object of my invention to provide an improved arrangement of this type by means of which the current for initially heating the electrodes to a temperature at which the free electron emission therefrom will support the normal discharge current will be interrupted and automatically after discharge through the device has been started.

My invention contemplates the provision of an electromagnet having a winding in one of the v supply lines on one side of one of the tube electrodes, a second winding between and in series with' the electrodes and in magnetic opposition to the first winding and a movable armature controlling make and break switch means, and it is a further object of my invention to provide in series with the second winding means adapted when the electrodes of the tube become heated to a temperature at whichthe free electron emission therefrom will support the normal discharge current to open automatically the switch means thereby cutting out the second winding and im-" parting a voltage surge to the tube to start normal discharge through the tube, the first winding serving to hold the armature in circuit-open position during discharge through the tube.

It is a further object of my invention to provide'an arrangement comprising but 'few parts which can be economically manufactured and assembled and which will be dependable and reliable in their automatic operation.

5 The invention consists of thenovel constructions, arrangements and devices to be hereinafter described and claimed for carrying out the above stated objects and such other objects as will appear from the following description of a cerp tain preferred embodiment illustrated in the accompanying drawing. I

Referring now to the drawing, the gaseous discharge tube III is provided with electrodes I I and I 2 which are in the form of coiled filaments and which may be oxide coated for greater electron 12 Claims. (01.176-124) OPERATING rk, Ill., assignor to Solo. 111., a corporation oi 1939, Serial No. 260,932

emission. The 'tube is 'filled, at least after the filaments are heated, with a gas such as mom or a mixture of gases such as helium and neon, or a source of vapor such as mercury. In starting a tube of this type it is first necessary to heat the electrodes to a temperature at which the electrons emitted therefrom are sufficient in number to supportthe normal discharge current between the'electrodes, and then to apply a voltage surge to the tube between the electrodes for starting discharge. The voltage of the surgeis greater thanthe normal operating voltage of the discharge device and may be of short duration. Failure to heat properly the filaments in a tube of this type before initiating discharge causes the discharge to be confined to one spot on each electrode whereby the electrodes are inlured.

Electric current, preferably alternating current, is supplied to the discharge device ID for initially-heating the filaments II and I2 and then for supporting discharge through the tube by supply lines I3 and I4. Supply line I3 is directly connected to filament I2 at its end I2a. An inductance or a choke coil I5 and a winding I6 of an electromagnet II are connected in series to the supply line I4. Winding I6 is in turn connected with the filament I I at its end I I a by means of lead I8. 1

The electromagnet I! has in addition to winding I6 two windings I9 and 2|]. Winding l9 has substantially the same number of turns but is in magnetic opposition to Winding I6. Winding which is a continuation of and is woundiin the same direction as winding resistor 2'I connected across it and is grounded to the frame of the electromagnet at '22. The three windings I6, I9 and 20 are placed on the core portion 23 of the electromagnet as shown diagrammatically in the drawing. The resistor 2| is of a material such as nickel which has a resistance that increases substantially with the temperature of the material.- Winding'IBof the electromagnet is connected by means of lead 24 with the filament at its end Ilb as shown.

A movable armature 25 is pivoted at 23a to the frame of .the electromagnet. The armature is held normally by a pull spring 26 against a stop 21 and spaced from the end 23b of the core bar'. The armature carries a switch element 28 and when the armature is in .the position shown in the drawing, the switch element 28. contacts with a second switch element 29 carried by a flexible arm 30, the arm being mounted on but insulated from the the core of the magnet-at 23c.

I9 has a shunting The arm 30 is connected by a lead 3| with the filament l2 at its end |2b. In the switch-closing position of the armature as shown in the drawing, the arm 30 is flexed upward slightly by the switch element 28 bearing on the switch element 29 and good contact between the switch elements is thus insured.

When a voltage is first applied between the supply lines l3 and M a heating current flows for heating the filaments H and, the circuit being from line H through inductance I5, winding l6, lead I8, filament lead 24, winding l9, winding 20 and resistor 2|, electromagnet core 23, armature 25, switch element 28, switch element 29, arm 30, lead 3|, filament I2 and finally to supply line l3. The windings l6 and I9 are connected in this circuit in opposition to each other and the net result of the heating current flowing through both windings is a magnetic flux substantially equal to zero. The resistor 2| is initially in a cold state and has a resistance much less than that of the parallel winding 20. The greater portion of the heating current, therefore, flows through the resistor rather than through the winding 20. The portion which does fiow through winding 20 is so small that it does not produce a magnetic flux in the core bar 23 great enough to pull the armature 25 down to the core bar against the action of the spring 26. However, the resistance 2| quickly heats up due to the action of the current passing through it and its resistance becomes greater and greater. More and more current flows through winding 20 producing a greater and greater resultant magnetic flux in the core bar 23. This magnetic flux soon becomes great enough to cause the'armature 25 to be pulled to the core, against the action of the spring 26, and the contact between the switch elements 28 and 29 is thus broken.

The sudden breaking of the circuit through the coils l9 and 20 of the electromagnet causes the magnetic fiux in the core to decrease suddenly, producing a relatively high voltage surge in winding Hi. This voltage surge added to the normal line voltage causes discharge to take place directly between the electrodes II and .|2. Once started, the discharge continues and the operating current flowing through winding I6 produces a magnetic flux in the core which acts to hold the armature in switch-opened position, and the circuit through the winding IS, the winding 20 and resistor 2 I, and the lead 3| connecting the filaments H and I2 remains open. There is, therefore, no power loss in those parts during discharge, and the resistor 2| consequently cools to the'temperature of the surrounding atmosphere.

When the operating discharge circuit is opened, as by switching off the device, the current discontinues to flow through holding coil l6, and the armature 25 under the action of spring 26 moves upwardly, thus again bringing the switch elements 28 and 29 into contact and completing the heating circuit. The arrangement is then again ready for the application of voltage to the supply leads for heating the filaments and starting discharge, and the cycle of operations is repeated.

The resistor 2| is selected with due consideration to the characteristics of the other circuit elements including the winding 20 and the filaments II and I2. The. resistor has such a resistance when cold, that is to say, such a temperature coeflicient of resistance, and such heat radiating properties that it will heat up and in conjunction with winding 20 cause the armature 25 to move toward the core bar and open the switch elements when or immediately after the filaments H and I2 have reached a temperature at which they emit sufficient electrons to support the normal discharge current between the electrodes.

The inductance |5 is suitable with alternating current and acts to stabilize the discharge through the gaseous discharge device. If direct current is used for the arrangement, a resistor should be used in place of the inductance.

It will be apparent from the foregoing description that my improved arrangement is of simple construction. The necessary parts may be economically manufactured and assembled on a production basis. The arrangement is entirely automatic in its operation, the electrodes of the tube are safeguarded by being preliminarily heated to a temperature at which the free electron emission therefrom will support the normal discharge current before the tube is placed in operation. Upon switching oif current to the gaseous discharge tube the make and break switch means associated with the electromagnet immediately close since current in that case no longer flows through the holding coil Hi. When current is again turned on it will not discharge directly from one electrode to the other in the tube unless the electrodes are at the desired operating temperature, in such case the current will fiow through the heating circuit including the second winding l9 and the resistor 2| and the third winding 20 until the electrodes are at a temperature at which the free electron emission therefrom will support the normal discharge current.

' I do not intend to limit the invention to the details shown and described, except only in so far as certain of the appended claims are specifically so limited, as it will be obvious that modifications may be made without departing from the principles of the invention.

I claim:

1. In a system of the class described; the combination of an electric gaseous discharge device having a cathode adapted to emit electrons when heated; circuit means connected with two supply lines for initially heating said cathode to a temperature at which the free electron emission therefrom will support the normal discharge current and then for supplying the operating current thereto; said circuit means including an electromagnetic switch having a holding coil in series with said cathode in one of said supply lines and a neutralizing coil between said cathode and the other supply line, and means for opening the switch and cutting out the neutralizing coil when the temperature of the cathode reaches the point at which the free electron emission therefrom will support the normal discharge current, the holding coil operating to hold the switch open during the discharge through the device.

2. In a, system of the class described; the combination of an electric gaseous discharge device having a cathode adapted to emit electrons when heated; circuit means connected with two supply therethrough,'means tending to hold the armature in circuit closing position, separating said switch elements the neutralizing coil when the temperature of the cathode reaches the pointat which the free electron emission therefromwill support the normal discharge current, the holding coil operating to hold the armature in open circuit position during the discharge through the device.

3. In a system of the class described; the combination of an electric gaseous discharge device having a cathode adapted toemit electrons when heated; circuit means connected with two supply lines for initially heating said cathode to a temperature at which the free electron emission therefrom will support the normal discharge current and then for supplying the operating current thereto; said circuit means including an electromagnet having a holding coil in series with said cathode in one of said supply lines, a neutralizing coil between the cathode and the other supply line, a third coil in serieswith said neutralizing and means for coil, a resistor in parallel with said third coil and a movable armature carrying a switch element,

a second switch element adapted to engage saidfirst switch element to close the circuit therethrough, means tending to hold the armature in circuit closing position, said resistor initially carrying suflicient current around said third coil to render it vinoperative but upon the temperature of the cathode reaching the point at which the free electron emission therefromwill support v the normal discharge current the resistance of said resistor is such that said third coil becomes operative to cause the armature to move into'open circuit position thereby rendering the holding coil effective and cutting out the other two coils.

4. In a system of the class described; the combination of an electric gaseous discharge device having a cathode adapted to emit electrons when heated; circuit means connected with two supply lines for initially heating said cathode to a'temperature at which the free electron emission therefrom will support the normal discharge current andthen for supplying the operating current thereto; and means for'supplying a delayed voltage surge to said discharge device comprising an electromagnet having a winding in series with said cathode in one of said supply lines and a second winding connected between said cathode and the other supply line and in magnetic opposition to the first winding, make and break switch means in series with said second winding, and means for opening said switch means and cutting out said second winding when the temperature of the cathode reaches the point at which the free electron emission therefrom will support the normal discharge current, the first winding op-' erating to hold the switch means open during the discharge through the deyice.

5. In a systemof the class described; the combination of an electric gaseous discharge device having a cathode adapted to'emit electrons when heated; circuit means connected with two supply lines for initially heating said cathode to a temperature at which the free electron emission therefrom will support the'normal discharge current and then for supplying the operating current thereto; and means for supplying a delayed voltage surge to said discharge device comprising an electromagnet having a holding coil in series with said cathode in one of said supply lines, a neutralizing coil between the cathode and the other supply line and a movable armature carrying a switch element, a second switch element adapted to engage said" first switch elementto and cutting out close the circuit therethrough, means tending to hold the armature in circuit closing position, and means for separating said switch elements and cutting out the neutralizing coil when the temperature of the cathode reaches the point at 5 which the free electron emission therefrom will support the normal discharge current, the holcling coil operating to hold the armature in open circuit position during the discharge through the device. 1 6. In a system of the class described; the combination of an electric gaseous discharge device having a cathode adapted to emit electrons when heated; circuit means connected with two. supply lines for initially heating said cathode to a teml perature at which the free electron emission therefrom will support the normal discharge current and then for supplying the operating current thereto; and means for supplying a delayed volt-- tralizing coil, a resistor in parallel with said third coil and a movable armature carrying a switch element, a second switch element adapted to engage said first switch element to close the circuit therethrough, means tending to hold the V armature in circuit closing position,- said resistor initially carrying suflicient current around said third coil to render it inoperative but upon the temperature of the cathode reaching the point at which the free electron emission therefrom will support the normal discharge current the 3 resistance of said resistor is such that said third coil becomesoperative to cause the armature to move into open circuit position thereby rendering the holding coil effective and cutting out the other two coils. o

7. In a system of the class described; the combination of an 'electricgaseous discharge tube having in each end an electrode adapted to emit electrons when'heated; circuit means connected with two supply lines for initially heating said electrodes to a temperature at which the free electron emission therefrom will support the normal discharge current therebetween and then for supplying the operating current thereto; said circuit means including an electromagnetic switch having a holding coil in series in one of the supply lines on one side of one of said electrodes and a neutralizing coil in seriesvwith and between said electrodes, and means for opening the switch and cutting out the neutralizing coil when the '55 temperature of the electrodes reaches the point at which the free electron emission therefrom will support the normal discharge current, the holding coil operating to hold the switch open during the discharge between the electrodes through the no tube.

8. In a system of the class described; the combination of an electric gaseous discharge tube having in each end an electrode adapted to emit electrons when heated; circuit means connected 5 with two supply lines for initially heating said electrodes to a temperature at which the free electron emission therefrom will support the normal discharge current therebetween and then for supplying the operating currentthereto; said cir- 7o sion therefrom will support the normal discharge current, the holding coil operating to hold the armature in open circuit position during the discharge between the electrodes through the tube.

9. In a system of the class described; the com- 7 bination of an electric gaseous discharge tube having in each end an electrode adapted to emit electrons when heated; circuit means connected with two supply lines for initially heating said electrodes to a temperature at which the free electron emission therefrom will support the normal discharge current therebetween and then for supplying the operating current thereto; said circuit means including an electromagnet having a holding coil in one of said supply lines on one side of one of said electrodesya neutralizing coil in series with and between said electrodes, a third coil in series with said neutralizing coil, a resistor in parallel with said third coil and a movable armature carrying a switch element, a second switch element adapted to engage said first switch element to close the circuit therethrough, means tending to hold the armature in circuit closing position, said resistor initially carrying suflicient current around said third coil to render it inoperative but upon the temperature of the electrodes reaching the point at which the free electron emission therefrom will support the normal discharge current the resistance of said resister is such that said third coil becomes operative to cause the armature to move into open circuit position thereby rendering the holding coil efiective and cutting out the other two coils.

10. In a system of the class described; the combination of an electric gaseous discharge tube having in each end an electrode adapted to emit electrons when heated; circuit means connected with two supply lines for initially heating said electrodes to a temperature at which the free electron emission therefrom will support the normal discharge current and then for supplying ,the operating current thereto; and means for supplying a delayed voltage surge to said discharge tube comprising an electromagnet having a winding in one of said supply lines on one side of one of said electrodes and a second winding in series with and between said electrodes and in magnetic opposition to the first winding, make and break switch means in series with said second winding, and means for opening said switch means and cutting out said second winding when the temperature of the electrodes reaches the point at which the free electron emission therefrom will support the normal discharge current,

the first winding operating to hold the switch means open during the discharge between the electrodes through the tube.

11. In a system of the class described; the combination of an electric gaseous discharge tube having in each end an electrode adapted to emit electrons when heated; circuit means connected with two supply lines for initially heating said electrodes to a temperature at which the free electron emission therefrom will support the normal discharge current and then for supplying the operating current thereto; and means for supplying a delayed voltage surge to said discharge tube comprising an electromagnet having a holding coil in one of said supply lines on one side of one of said electrodes, a neutralizing coil in series with and between the electrodes and a movable armature carrying a switch element, a second switch element adapted to engage said first switch element to close the circuit therethrough, means tending to hold the armature in circuit closing position, and means for separating said switch elements and cutting out the neutralizing coil when the temperature of the electrodes reaches the point at which the free electron emission therefrom will support the normal discharge current, the holding coil operating to hold the armature in open circuit position during the discharge between-the electrodes through the tube.

12. In a system of the class described; the combination of an electric gaseous discharge tube having in each end an electrode adapted to emit electrons when heated; circuit means connected with two supply lines for initially heating said electrodes to a temperature at which the' free electron emission therefrom will support the normal discharge current and then for supplying the operating current thereto; and means for supplying a delayed voltage'surge to said discharge tube comprising an electromagnet having a holding coil in one of said supply lines on one side of one of said electrodes, a neutralizing coil in series with and between said electrodes, a third coil in series with said neutralizing coil, a resistor in parallel with said third coil and a movable armature carrying a switch element, a second switch element adapted to engage said first switch element to close the circuit therethrough, means tending to hold the armature in circuit closing position, said resistor initially carrying sufficient current around said third coil to render it inoperative but upon the temperature of the electrodes reaching the point at which the free electron emission therefrom will support the normal discharge current the resistance of said resistor is such that said third coil becomes operative to cause the armature to move into open circuit position thereby-rendering the holding coil eifective and cutting out the other two coils.

JosEPH G. SOLA. 

